Interpretive Summary: Brucella abortus is a bacteria that can cause disease in domestic livestock and people. National eradication programs have been ongoing for decades in an effort to eliminate this disease and protect public health. The persistence of Brucella abortus in bison and elk near Yellowstone National Park is controversial. However, persistence of brucellosis in these reservoirs is a threat for transmission of disease to domestic livestock. In this study, we found that bison had a higher incidence of abortion and infection after experimental challenge than cattle. However, the numbers of bacteria within tissues were similar between cattle and bison. Overall, our study demonstrates similarities and differences between bison and cattle after experimental infection with Brucella abortus. This data will be of benefit to the scientists, livestock producers, and regulatory personnel in understanding the epidemiology and diagnostic responses associated with Brucella abortus infection of bison and cattle.

Technical Abstract:
A comparative study was conducted using data from naive bison (n=45) and cattle (n=46) from 8 and 6 studies, respectively, in which a standardized Brucella abortus strain 2308 experimental challenge was administered. The incidence of abortion, fetal infection, uterine or mammary infection, or infection in maternal tissues after experimental challenge was greater (P<0.05) in bison as compared to cattle. In animals that did abort, the time between experimental challenge and abortion was shorter (P<0.05) for bison when compared to cattle. Brucella colonization of four target tissues, and serologic responses on the standard tube agglutination test at the time of abortion, did not differ (P>0.05) between cattle and bison. The results of our study suggest that naive bison and cattle have similarities and differences after experimental exposure to a virulent B. abortus strain. Although our data suggests that bison may be more susceptible to infection with Brucella, some pathogenic characteristics of brucellosis were similar between bison and cattle.